1. Field of Invention
The present invention relates to heptaprenyl diphosphate (hereunder sometimes abbreviated to "HDP") synthetase of Bacillus stearothermophilus origin, to DNA encoding the enzyme, to an expression vector containing the DNA, to a host transformed by the expression vector, to a method of producing heptaprenyl diphosphate-synthesizing enzyme by the host, and to a method of producing heptaprenyl diphosphate using the enzyme or host.
2. Related Art
HDP, synthesized from condensation reaction of 4 molecules of isopentenyl diphosphate and 1 molecule of farnesyl diphosphate by HDP-synthetase, is an important: biosynthetic intermediate of isoprenoids such as prenylquinone. Although HDP-synthetase, which is categorized into prenyl transferase, is known to be present in some microorganisms such as Bacillus subtilis (J. Biol. Chem. 255, p.4539-4543 (1980)), its amino acid sequence and the DNA sequence of the gene encoding it have not been known.
Genes coding for other prenyl transferase are known, farnesyl diphosphate synthetase ([2.5.1.1.] J. Biol. Chem. 265, p.4607-4614 (1990)), geranylgeranyl diphosphate synthetase (Proc. Natl. Acad. Sci. USA, 89, p.6761-6764). However, the tertiary structures of the known prenyl transferases are homodimers which comprise two identical subunits, and it is different from the peculiar heterodimer of Bacillus subtilis HDP synthetase (FEBS Lett. 161, 257-260 (1983)). Therefore, absolutely no data exists regarding homology between the amino acid sequences of the former two and the latter.
Consequently, the present invention is aimed at providing HDP synthetase of Bacillus stearothermophilus origin, which was hitherto unknown in the species, DNA encoding the enzyme, and a method of production of the recombinant HDP synthetase using the DNA.